The present invention relates to a mutant allele of soybean designated SG-ULRFO which results in an ultra-low raffinose and stachyose phenotype. The present invention also relates to a soybean seed, a soybean plant and parts of a soybean plant and a soybean hybrid which comprises the mutant allele. In addition, the present invention is directed to transferring the SG-ULRFO mutant allele to other soybean plants. The present invention also relates to novel polymorphisms of soybean raffinose synthase genes that associate with an ultra-low raffinose and stachyose phenotype. The present invention also relates to new soybeans having both an ultra-low raffinose and stachyose phenotype while having high germination rates. All publications cited in this application are herein incorporated by reference.
Soybean [Glycine max (L.) Merr.] represents one of the most important economic crops in the United States and is considered to be similar in importance to corn (zea mays L.) in acreage and second only to corn in value (Sleper and Poehlman, 2006). The oil, protein, and carbohydrate composition of the soybean seed generally controls its use. Seeds of soybean cultivars in the United States have an average composition of 20% oil, 40% protein, and 15% soluble carbohydrates in dry weights of cotyledons of ungerminated seeds (Hsu et al., 1973).
Soybean meal is a major component of the diets of monogastric animals and its usefulness is determined, in part, by the carbohydrate component. The carbohydrate component of soybean meal is comprised of three major oligosaccharides: sucrose, raffinose, and stachyose. (Openshaw and Hadley, 1978). Of the three, only sucrose is nutritionally useful and can be fully digested by monogastric animals. Raffinose and stachyose are considered anti-nutritional units because they cannot be digested due to the lack of a-galactosidase activity in the gut of monogastric animals. Removing raffinose and stachyose from soybean meal has been reported to increase the metabolizable energy of the diet by as much as 20%. (Coon et al., 1990). The effects of raffinose and stachyose in diets have been studied in pigs (Smiricky et al., 2002)), dogs (Zuo et al., 1996)), chickens (Parsons et al., 2000)), and humans (Suarez et al., 1999)). Generally, raffinose and stachyose are poorly digested by monogastrics; the removal of raffinose and stachyose from soybean meal increases the metabolizable energy of the diet and reduces flatulent production. (Coon et al., (1990); Parsons et al., (2000); Suarez et al., (1999).
Extensive botanical surveys of the occurrence of raffinose and stachyose have been reported in the scientific literature. See, Dey, P. M., In Biochemistry of Storage Carbohydrates in Green Plants, Academic Press, London, pp. 53-129 (1985). Raffinose and stachyose are thought to be second only to sucrose among the nonstructural carbohydrates with respect to abundance in the plant kingdom. In fact, raffinose and stachyose may be ubiquitous, at least among higher plants. Raffinose and stachyose accumulate in significant quantities in the edible portion of many economically significant crop species. Examples include soybean (Glycine max L. Merrill), sugar beet (Beta vulgaris), cotton (Gossypium hirsutum L.), canola (Brassica sp.) and all of the major edible leguminous crops including beans (Phaseolus sp.), chick pea (Cicer arietinum), cowpea (Vigna unguiculata), mung bean (Vigna radiata), peas (Pisum sativum), lentil (Lens culinaris) and lupine (Lupinus sp.).
The biosynthesis of raffinose and stachyose has been fairly well characterized. See, Dey, P. M., In Biochemistry of Storage Carbohydrates in Green Plants (1985). The committed reaction of raffinose and stachyose biosynthesis involves the synthesis of galactinol from UDP galactose and myo-inositol. The enzyme that catalyzes this reaction is galactinol synthase. Synthesis of raffinose and higher homologs in the raffinose and stachyose from sucrose is thought to be catalyzed by distinct galactosyltransferases (e.g., raffinose synthase, stachyose synthase, etc.).
In addition to evaluating plants at the molecular level, plant breeding is an important area in the development of any novel, desirable plant germplasm. Plant breeding begins with the analysis and definition of problems and weaknesses of the current germplasm, the establishment of program goals, and the definition of specific breeding objectives. The next step is selection of germplasm that possesses the traits to meet the program goals. These important traits may include higher seed yield, resistance to diseases and insects, better stems and roots, tolerance to drought and heat, and better agronomic quality.
The complexity of inheritance influences choice of the breeding method when developing new soybean lines. Backcross breeding is used to transfer one or a few favorable genes for a highly heritable trait into a desirable cultivar. This approach has been used extensively for breeding disease-resistant cultivars. Various recurrent selection techniques are used to improve quantitatively inherited traits controlled by numerous genes. The use of recurrent selection in self-pollinating crops depends on the ease of pollination, the frequency of successful hybrids from each pollination and the number of hybrid offspring from each successful cross.
Each breeding program should include a periodic, objective evaluation of the efficiency of the breeding procedure. Evaluation criteria vary depending on the goal and objectives, but should include gain from selection per year based on comparisons to an appropriate standard, overall value of the advanced breeding lines, and number of successful lines produced per unit of input (e.g., per year, per dollar expended, etc.).
A most difficult task is the identification of lines that are genetically superior, because for most traits the true genotypic value is masked by other confounding plant traits or environmental factors. One method of identifying a superior plant is to observe its performance relative to other experimental plants and to a widely grown standard cultivar. If a single observation is inconclusive, replicated observations provide a better estimate of its genetic worth.
In addition to phenotypic observations, the genotype of a plant can also be examined. There are many laboratory-based techniques available for the analysis, comparison and characterization of plant genotype; among these are Isozyme Electrophoresis, Restriction Fragment Length Polymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs), Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA Amplification Fingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs), Amplified Fragment Length polymorphisms (AFLPs), Simple Sequence Repeats (SSRs—which are also referred to as Microsatellites), and Single Nucleotide Polymorphisms (SNPs).
Soybean, Glycine max (L), is an important and valuable field crop. Thus, a continuing goal of soybean plant breeders is to develop stable, high yielding soybean lines with important commercial and agronomic traits.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification.